Extract Class: StrictColumnWidthsParser.

This extracts a class to handle the splitting of a line into its columns
based off of the preset breakpoints.

The purpose of splitting this behavior out into a separate class is so
that the code can be reused by other column parsers.  This new class is
*not* meant to be part of the public API of this package.
seems like these data strings should be local to each test. Having them tied together can make small implementation changes later have to change extra tests. Or changing test data to catch something that wasn't thought of affect another test without noticing.